The goal of this research is to determine the feasibility of combining three-channel recording of the Auditory Brainstem Response (ABR) with a stimulus-pairs technique so as to measure the decrement in response that occurs in the Relative Refractory Period (RRP). This method will permit detection of any abnormalities which affect the RRP, since the parameters can be adjusted so that there is decrement in the response to the 2nd stimulus, in normals. The 3-Channel Lissajous Trajectory (3-CLT) of the ABR will be analyzed with respect to both linear and planar segments. The use of stimulus pairs provides information about the responses to both the 1st and the 2nd stimulus (in the RRP), and also permits analysis of the neuronal activity which is NOT activated in the RRP (by means of the "ghost" waveforms recovered by subtraction of the 1st and 2nd responses). This methodology is likely to be more sensitive to pathological changes in the auditory nervous system than is the ABR, which has had extensive use in audiology and neurology as a objective measure of brainstem normality or abnormality. Keywords: auditory brainstem response; evoked response; three- channel Lissajous trajectory; planar analysis; stimulus pairs; refractory period; three-dimensional analysis Potential commercial applications: The automated data acquisition and analysis system that will be designed using microcomputers is intend to be a basis for advanced evoked response recording systems of the future. At least six companies now produce ABR systems, primarily for clinical use, but the these systems cannot record or analyze either the 3-CLT or stimulus pairs, much less the two combined. This research will provide a hardware/software design which can be incorporated into a commercial product, as well as the scientific justification for its use. The design will either be sold or licensed to companies with production and sales capabilities.